Rufus spaulding merrill



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N. PETERS, PHOTO-UTHOGRAPH Qtnitrh giant gaunt @ffibr.

RUFUS SPAULDINGZVMERRILL, or BOSTON, Assreiron TOVVHIMSELF, LEVI LISOOM, AND WILLIAM LINCOLN, OFBROOKLINE,MASSACHUSETTS.

Letters Patent No. 78,000, dated May 19, 1868.

IMPROVEMENT IN BRIDGES.

TO WHOM IT MAY CONCERN Be it known that I, Rurus SrAoLmsc Mnnarnn, of Boston, in the county, of' Sufi'olk, and State of Marisaohusetts, have invented certain new and useful Improvement-s in the Construction of Bridges; ;and I hereby,

declare the following to boa-full, clear, and exact description of the'same, reference being'had to the accompanying drawings, in which--- l Figure 1 is a longitudinal vertical section, entire linen; y, fig. 2. Figure 2 is a plan view of a bridge 'made in accordance with my invention; andlii ure 3 is a transverse verticalsection thro u b one of the sides of the brid e and re resents more. clear] a i g v t:

the details of construction. a p p e My invention relates to-that kind of bridge for which Letters Patent of the UnitedStates have been heretofore issued to A. Cottrell, and also to Levi Liscom, that is to say, abridge built byprojecting, from the opposite shores or banks, levers composed of snperposedllayers ofbeams, projecting one inadvance oi the other,

until the opposite levers meet at or about the centre of the space to be spanned.

Heretofore, all such bridges have been made of wood, as it has been deemed impracticable to build them of iron. My object, however, has been toovercomethe diflicnlties which have prevented the use of the latter material for this purpose, and-in attaining this result, I have developed certain improvementsin the construction of the bridge, and in the combination of its parts, which are the subject ,of the present patent. I

The material'used 'by me in the construction of the bridge is angle-irom'oriron plates, along the edges or sides of which are formed flanges or angle-irons of the desired breadth. Plates of each layer are placed as it were on edge, or so that their bottom flange shall rest on the support below, while the upper flange. or.anglciron will be in readiness to receive and support the platesrof which thesuperin'oumbent layer is composed. Each lever is composed of two parallel series ofthese plates, thus arranged in layers, connected by means of upright angle-iron plates,-t0 which they are all secnrely riv'etedor bolted. I

To enable others to better understand=these and other features of my inventwn, I will proceed, however, to describe-more particularly the manner in which the'said invention is or may be carried into effect, by'reference to the drawings accompanying and forming part offthis specification,"

: The different layers of angle-iron plates of which each lever is composed, are indicated by the letters a a a a &c. Those layers project one in advance of the other, as indicated in fig. 1, the shore-end of the lever 7 being weighted, as the projection increases, sons to compensate for the augmented weight of its projecting ends From each bank or shore two of these levers, A and A, are thus projected, meeting the opposite levers in about the centre of the space to be spanned. The levers A A are connected by means of transverse beams B, fig. 1 (also shown in broken lines, fig. 2,) which are added as the difi'erent layers lire completed; and serve to sustain a temporary flooring, over which the materials needed for the construction of the bridge are carried during the progress of the work.

The form of the plates of which the layers a a, &c., are composed, is shown clearly in fig. 3. Each plate is provided with top and bottom .flanges or angle-irons 1 2, which project at right angles from theface of the plate. Informing either of the levers A A, two parallel layers of angle-iron plates (fig. 3) are laid upon the foundation C, and are bolted to upright beams of angle-iron D, placed between the parallel layers, as repre sented in figs. 2 and 3. Each layer is not of course composed of a single continuous plate, bnt of a number of plates, according to thelength required for the layer. The plates rest'upon their bottom flanges. 2. Upon the' layers a are placed the plates, which are to compose the layer next above, the flanges 2 of the latter plates rests ing upon the flange 1 of the former. l

When in this position the plates of layers a are also bolted or riveted to the upright angle-ipon beams D, while their flanges 2 are in like manner riveted tothe contiguous flanges lot the plates. beneath. In this manner layer after layer is added, eaeh projectingjn advance of the one below, the prescribed distance, as repre;

sented in fig. 1, and secured to the uprights D, and to the flanges of thelayers' next above and below, in the manner illustrated fully in fig. 3.

In proportion as the projection or length of the lever. increases, uprights-D are added, placed at a. suitable distance spent, so as to give the necessarystiffness and solidityto the lever. The two levers A A are both built at the same time, and during the process of the work the transverse beams B, which are also. of angleiron, are laid, connecting the two, and serving as a support -for.a temporary flooring," over which the material needed in construetioncan be conveyed: of course understoodthat as the projection of the bridge increases, the"'shore-ends"of the levers 'are'wi'ghted by masonry or other suitable means,-so as to counterbalance the increased weightof their projecting ends.

'In order to form the n'ec'essary truss on each side of the bridge, the length of every'other upright angle iron'beam D is gradually increased as they approach the centre of the bridge, so as to form the-uprights upon which the'top chord E of the truss issecured and held, as shown in fig. 1. As these uprights are also connected, as above explained, 'tvith the different layers of plates of which the levers are composed, it will be seen that the whole structure is solidly and firmly held together, and thatxthe whole bridge may be said in efi'ect to constitute thebottomchord of the truss. The uprights to which the top chords F are attached, are strengthened or braced.

by means of cross-ties F, which may' be also of angle-iron; the top chords E of course, plated in position 7 after the levers projected from theoppo'siteshores have met, and been united by means of the topmost layer a which extends the whole length of the bridge. The transverse angle-iron beams G are then laid, extending between the levers AA, theirends being held between 'the'flanges 1 2 of the plates of the topmost layers a, and up n these beams the permanent flooring of the bridge is laid. I

By this means, and'at a comparatively small expense, I am enabled to builds. bridge of this kind entirely of iron, and in such manneras to obtain the greatest strength and stififnes s The plates of which the levers nrenrade caneither be rolled in the form shown in cross-sections in fig. 3, or they maybe ordinary plates of the requisite-width, with angle-irons riveted totheir top and bottom.

Instead of making the flanges or angle-irons both to project, from the same side of the plate, one flange may been one side and the other on the other side,but I prefer the form shown in the drawings as giving the best results. 7

Having now described my invention, and the mannerin which the same is or may be carried into efl'ect, what T claim, and desire to secure by Letters Patent, is-- The construction of iron bridges, substantially'in the manner herein described. In testimony whereof,- I have signed my name to this specification before two subscribing witnesses.

' I .RUFUS S. MERRILL;

Witnesses:

EDM. F. BROWN,

Guns. G. PAGE, Jr. 

